The present invention relates to the field of webs that can be made by weaving threads so as to posses a determined void factor. In the meaning of the invention, it should be assumed that the interlaced threads of such webs define meshes of selected void factor, but without the term xe2x80x9cmeshxe2x80x9d necessarily indicating that the subject matter of the invention is directed essentially towards webs that have been obtained not by weaving but by knitting, to give rise to the meshes being formed by interlaced thread(s). [Translator""s note: the French word for xe2x80x9cmeshxe2x80x9d, i.e. maille, is also a synonym for xe2x80x9cknittingxe2x80x9d].
The invention relates to meshed webs for constituting blinds or curtains in panels and/or strips that can be used indoors or outdoors relative to one or more windows or the like.
Such curtains or blinds generally serve to attenuate the amount of light that passes in the event of bright light and/or to constitute a kind of screen that provides a contribution to thermal insulation, particularly when such screens are placed on the outside of such windows.
Webs of the above type are generally coated in a thermoplastic material, either by prior-coating of the threads or by coating the web by soaking, with such coating being intended to give appropriate resistance to aging, more particularly when installation is to be on the outside. Coating should also generally be considered as having a specific bonding function so as to establish heat sealing bonds between the interlaced threads which are woven using a weave which can be of any kind insofar as it allows a non-negligible void factor to remain, of the type to be found in articles sold as screens for attenuating the passage of light.
In such applications, it must be understood that curtains and stores of the above-type can be considered as providing satisfaction for one and/or the other of the attenuation and thermal insulation functions.
Nevertheless, for some time the need has been felt for a web that possesses a void factor that is not constant so as to be able to make advantage of greater or lesser passage or absorption of light in some determined zone whose specific location depends essentially on the application.
In the meaning of the invention, the determined zone in question can be that situated at the bottom of the curtain or blind or indeed the top thereof, and in some cases, the middle portion of the curtain or blind when it is in its deployed or unrolled state. It can be considered that the prior art does not at present enable such a need to be satisfied, at any rate to the knowledge of the Applicant. The object of the invention is specifically to mitigate that omission and to make it possible to supply a meshed web that can be made so as to produce a local portion having a different void factor in a clearly defined zone, or on the contrary in which variation takes place progressively.
To achieve the intended objects, the web of the invention for constituting a screen having the function of attenuating light and/or of providing thermal insulation is characterized in that it is made up of two sheets of threads of organic or inorganic material that are interlaced to define meshes, locally defining a zone that has a mesh void factor that is different from that of the remainder of the web.
Various other characteristics appear from the following description given with reference to the accompanying drawings which show embodiments of the invention as non-limiting examples.